#include<bits/stdc++.h>
using namespace std;

int fac(int x)
{
	int s=1;
	for (int i=1;i<=x;i++)
		s*=i;
	return s;
}

int main()
{
	int m,n;
	cin>>m>>n;
	cout<<fac(m)/(fac(m-n)*fac(n))<<endl;
	return 0;
}